Static printed material may be thought of as a form of read only memory which requires no power and stores its data in a form visible to the human eye. Additionally, the data is presented generally in a format comfortable for human eye reading which presents printed text against a contrasting physical background of white or another contrasting colored paper. Furthermore, a large amount of information can be stored in printed material such as a textbook. However, the permanent setting of literary content on cards, books, magazines and other printed mediums for expressing literary content also means the content does not adapt to the reader.